1/**************************************************************************
2 *
3 * Copyright 2006 Tungsten Graphics, Inc., Bismarck, ND., USA.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
21 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
22 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
23 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
24 * USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 *
27 **************************************************************************/
28
29/*
30 * Generic simple memory manager implementation. Intended to be used as a base
31 * class implementation for more advanced memory managers.
32 *
33 * Note that the algorithm used is quite simple and there might be substantial
34 * performance gains if a smarter free list is implemented. Currently it is just an
35 * unordered stack of free regions. This could easily be improved if an RB-tree
36 * is used instead. At least if we expect heavy fragmentation.
37 *
38 * Aligned allocations can also see improvement.
39 *
40 * Authors:
41 * Thomas Hellstr�m <thomas-at-tungstengraphics-dot-com>
42 */
43
44#include "drmP.h"
45#include <linux/slab.h>
46
47unsigned long drm_mm_tail_space(drm_mm_t *mm)
48{
49	struct list_head *tail_node;
50	drm_mm_node_t *entry;
51
52	tail_node = mm->ml_entry.prev;
53	entry = list_entry(tail_node, drm_mm_node_t, ml_entry);
54	if (!entry->free)
55		return 0;
56
57	return entry->size;
58}
59
60int drm_mm_remove_space_from_tail(drm_mm_t *mm, unsigned long size)
61{
62	struct list_head *tail_node;
63	drm_mm_node_t *entry;
64
65	tail_node = mm->ml_entry.prev;
66	entry = list_entry(tail_node, drm_mm_node_t, ml_entry);
67	if (!entry->free)
68		return -ENOMEM;
69
70	if (entry->size <= size)
71		return -ENOMEM;
72
73	entry->size -= size;
74	return 0;
75}
76
77
78static int drm_mm_create_tail_node(drm_mm_t *mm,
79			    unsigned long start,
80			    unsigned long size)
81{
82	drm_mm_node_t *child;
83
84	child = (drm_mm_node_t *)
85		drm_alloc(sizeof(*child), DRM_MEM_MM);
86	if (!child)
87		return -ENOMEM;
88
89	child->free = 1;
90	child->size = size;
91	child->start = start;
92	child->mm = mm;
93
94	list_add_tail(&child->ml_entry, &mm->ml_entry);
95	list_add_tail(&child->fl_entry, &mm->fl_entry);
96
97	return 0;
98}
99
100
101int drm_mm_add_space_to_tail(drm_mm_t *mm, unsigned long size)
102{
103	struct list_head *tail_node;
104	drm_mm_node_t *entry;
105
106	tail_node = mm->ml_entry.prev;
107	entry = list_entry(tail_node, drm_mm_node_t, ml_entry);
108	if (!entry->free) {
109		return drm_mm_create_tail_node(mm, entry->start + entry->size, size);
110	}
111	entry->size += size;
112	return 0;
113}
114
115static drm_mm_node_t *drm_mm_split_at_start(drm_mm_node_t *parent,
116					    unsigned long size)
117{
118	drm_mm_node_t *child;
119
120	child = (drm_mm_node_t *)
121		drm_alloc(sizeof(*child), DRM_MEM_MM);
122	if (!child)
123		return NULL;
124
125	INIT_LIST_HEAD(&child->fl_entry);
126
127	child->free = 0;
128	child->size = size;
129	child->start = parent->start;
130	child->mm = parent->mm;
131
132	list_add_tail(&child->ml_entry, &parent->ml_entry);
133	INIT_LIST_HEAD(&child->fl_entry);
134
135	parent->size -= size;
136	parent->start += size;
137	return child;
138}
139
140
141
142drm_mm_node_t *drm_mm_get_block(drm_mm_node_t * parent,
143				unsigned long size, unsigned alignment)
144{
145
146	drm_mm_node_t *align_splitoff = NULL;
147	drm_mm_node_t *child;
148	unsigned tmp = 0;
149
150	if (alignment)
151		tmp = parent->start % alignment;
152
153	if (tmp) {
154		align_splitoff = drm_mm_split_at_start(parent, alignment - tmp);
155		if (!align_splitoff)
156			return NULL;
157	}
158
159	if (parent->size == size) {
160		list_del_init(&parent->fl_entry);
161		parent->free = 0;
162		return parent;
163	} else {
164		child = drm_mm_split_at_start(parent, size);
165	}
166
167	if (align_splitoff)
168		drm_mm_put_block(align_splitoff);
169
170	return child;
171}
172
173/*
174 * Put a block. Merge with the previous and / or next block if they are free.
175 * Otherwise add to the free stack.
176 */
177
178void drm_mm_put_block(drm_mm_node_t * cur)
179{
180
181	drm_mm_t *mm = cur->mm;
182	struct list_head *cur_head = &cur->ml_entry;
183	struct list_head *root_head = &mm->ml_entry;
184	drm_mm_node_t *prev_node = NULL;
185	drm_mm_node_t *next_node;
186
187	int merged = 0;
188
189	if (cur_head->prev != root_head) {
190		prev_node = list_entry(cur_head->prev, drm_mm_node_t, ml_entry);
191		if (prev_node->free) {
192			prev_node->size += cur->size;
193			merged = 1;
194		}
195	}
196	if (cur_head->next != root_head) {
197		next_node = list_entry(cur_head->next, drm_mm_node_t, ml_entry);
198		if (next_node->free) {
199			if (merged) {
200				prev_node->size += next_node->size;
201				list_del(&next_node->ml_entry);
202				list_del(&next_node->fl_entry);
203				drm_free(next_node, sizeof(*next_node),
204					 DRM_MEM_MM);
205			} else {
206				next_node->size += cur->size;
207				next_node->start = cur->start;
208				merged = 1;
209			}
210		}
211	}
212	if (!merged) {
213		cur->free = 1;
214		list_add(&cur->fl_entry, &mm->fl_entry);
215	} else {
216		list_del(&cur->ml_entry);
217		drm_free(cur, sizeof(*cur), DRM_MEM_MM);
218	}
219}
220
221drm_mm_node_t *drm_mm_search_free(const drm_mm_t * mm,
222				  unsigned long size,
223				  unsigned alignment, int best_match)
224{
225	struct list_head *list;
226	const struct list_head *free_stack = &mm->fl_entry;
227	drm_mm_node_t *entry;
228	drm_mm_node_t *best;
229	unsigned long best_size;
230	unsigned wasted;
231
232	best = NULL;
233	best_size = ~0UL;
234
235	list_for_each(list, free_stack) {
236		entry = list_entry(list, drm_mm_node_t, fl_entry);
237		wasted = 0;
238
239		if (entry->size < size)
240			continue;
241
242		if (alignment) {
243			register unsigned tmp = entry->start % alignment;
244			if (tmp)
245				wasted += alignment - tmp;
246		}
247
248
249		if (entry->size >= size + wasted) {
250			if (!best_match)
251				return entry;
252			if (size < best_size) {
253				best = entry;
254				best_size = entry->size;
255			}
256		}
257	}
258
259	return best;
260}
261
262int drm_mm_clean(drm_mm_t * mm)
263{
264	struct list_head *head = &mm->ml_entry;
265
266	return (head->next->next == head);
267}
268
269int drm_mm_init(drm_mm_t * mm, unsigned long start, unsigned long size)
270{
271	INIT_LIST_HEAD(&mm->ml_entry);
272	INIT_LIST_HEAD(&mm->fl_entry);
273
274	return drm_mm_create_tail_node(mm, start, size);
275}
276
277
278void drm_mm_takedown(drm_mm_t * mm)
279{
280	struct list_head *bnode = mm->fl_entry.next;
281	drm_mm_node_t *entry;
282
283	entry = list_entry(bnode, drm_mm_node_t, fl_entry);
284
285	if (entry->ml_entry.next != &mm->ml_entry ||
286	    entry->fl_entry.next != &mm->fl_entry) {
287		DRM_ERROR("Memory manager not clean. Delaying takedown\n");
288		return;
289	}
290
291	list_del(&entry->fl_entry);
292	list_del(&entry->ml_entry);
293
294	drm_free(entry, sizeof(*entry), DRM_MEM_MM);
295}
296